The Urban Suburban Part 2 - 1947 Chevrolet Delivery Panel

RB's Urban Suburban Gets a New Chassis

By Bruce Caldwell

Photography by Scott Doe

Hot rods and houses both benefit from solid foundations. There are building codes that prevent homeowners from using rotten timbers in foundations, but street rodders have to rely on their own common sense. Too often, do-it-yourself rod builders will compromise on a marginal chassis only to find out later that it was an exercise in futility.

An original '40s or '50s chassis that didn't seem too bad at first glance can turn into an endless repair project. By the time you add everything up, the "fixer" chassis could cost as much as if you'd started with a new one. Builders of vehicles like '47-54 Chevy/GMC 1/2-ton trucks previously didn't have many options, short of having a one-off custom chassis built. They could do a little traveling to find a relatively rust-free chassis (usually a wise move), but they didn't have the options that are available to builders of '20s and '30s Ford street rods.

Ray Doe at RB's Obsolete Automotive in Edmonds, Washington, recognized the need for a rolling chassis for '47-54 GM trucks. His company offers lots of components for modernizing an original frame, but there is still the issue of condition for rails that are 50 years old. Any chassis that old is liable to have problems, but these trucks are from an era when trucks were beasts of burden. Most of them were driven hard and put away wet.

Ray's solution was to design and build a totally new rolling chassis for the '47-54 (and '55 first-series models) GM pickups, panels, and Suburbans. The test bed for the new chassis is the Urban Suburban project being covered here.

NEW AND IMPROVED
Unlike detergents, the Serious Hardware rolling chassis really is new. It's stronger and much improved over the stock units. The 4-inch bent tubular chassis is dimensionally smaller but stronger than the GM versions, even when they were fresh from the factory. Engines like the Chevy big-block hadn't been conceived when these trucks were new, so there wasn't any need to build a chassis strong enough to handle 500-plus horsepower. The crew at RB's figured they might as well make the chassis street rodder-friendly since they were starting with a clean sheet of paper.

One of the biggest differences is the width of the framerails behind the cab. Not many street rodders favor the tall, skinny, OEM-style wheels and tires, so the new chassis is a total of 4 inches narrower than the old one. Each side is 2 inches narrower, so almost any tire (short of Pro Street steamrollers) will fit without altering the framerails.

The stock frame gets progressively wider as it approaches the rear crossmember. RB's new chassis is the same width as stock at the back of the cab, but from there the rails were moved inboard so that there is an extra 2 inches by each wheel. Even though the frame is narrower, all the factory cab, bed, running board, and bumper mounting points are exactly where they should be. The radiator core support is also in its correct position.

Either a Chevy small-block or big-block V-8 can be used along with several popular GM automatic transmissions, including the Turbo 350 and Turbo 400, plus the various late-model electronic overdrive transmissions. The rearend is a 9-inch Ford with 3.0:1 standard gears. Parallel rear leaf springs and tubular shocks support the rearend. The springs are E-Z Slide units for a smooth ride. Eleven-inch front disc brakes and drum rear brakes are part of the package, although optional rear disc brakes can be added, as can bigger front discs. A brake booster is helpful when stopping a full-size pickup. A 9-inch booster and dual master cylinder, plus the corresponding linkage and brake pedal, are part of the chassis package. In keeping with the street rodder-friendliness theme, the booster is mounted on the outside of the framerails. This keeps it off the firewall and away from the exhaust system.

A new-design, bent tubular front crossmember provides a strong base for the independent front suspension. The crossmember has integrated lower control arm mounts. The hybrid system was designed especially for trucks and heavy engines. The tubular upper and lower control arms have their correct ball joints.

It might sound redundant to emphasize that the lower control arms have true lower ball joints since that seems self-explanatory. Unfortunately, many street rod front suspension setups use the upper ball joints in both control arms. The upper ball joints aren't as heavy duty as the lower ones. Only true lower ball joints are designed to handle the greater stresses placed on the lower control arms. RB's Obsolete was adamant that their truck chassis have this important safety advantage.

The upper control arms can be adjusted with shims like a regular passenger car. A new power rack mounts in front of the crossmember. Standard-height spindles are included, but optional dropped ones can be added. A front antisway bar helps give a level of handling never dreamed of by the original owners of these classic pickups. An optional rear antisway bar is also available.

DO THE MATH
A complete truck chassis isn't something you can get in a blister pack at the 7-11 checkout counter. The current price of RB's chassis is $7,499 plus shipping. The chassis is shipped assembled, but not painted. That way you know everything is there and where it should be.

The price might be a little intimidating until you do some comparison-shopping. RB's has sold (and continues to do so) lots of separate components for this series of trucks. If you were to order their bolt-in front crossmember kit with Mustang II components, a power rack, front and rear brakes, motor mounts, brake booster, rear parallel leaf spring kit, Currie 9-inch rearend, transmission crossmember, front antisway bar, and everything else needed to make a relatively comparable chassis, the total would be just short of $4,500 plus shipping and handling.

That might seem like a substantial savings until you factor in the labor costs for cleaning and repairing the old chassis. If you want to run big rear tires, narrowing the rear framerails will add a lot to your total. The new chassis has many superior features that can't be had with the old chassis, so some value should be assigned to these factors.

RB's likes to figure your old chassis as being worth $1 grand to a restorer or budget truck builder, but as the diet ads warn, "Results may vary." They might be a little optimistic about the old chassis value, but the figure is based on condition and local demand. Unless it is total trash, it should be worth something. If the old chassis were unusable, you'd have to pay for a better one before you could add the bolt-in front suspension kit and other parts.

The more ways you run the numbers, the better the complete new chassis looks. When all the true costs (whether you pay someone to do the work or place a value on your own time) are included, the new chassis makes good financial sense. And, most importantly, everything is new. You are essentially building a new truck that resembles the original, so why not start with a solid foundation?